How can I get the Global navigation to ignore the core4.css and take up my custom styles.
Thanks
You can simply do this by including the following part in your html master.
<!--SPM:<SharePoint:CssRegistration Name="/_catalogs/masterpage/custom/css/custom-core.css" After="corev15.css" runat="server"/>-->
In the file »custom-core.css« you can simply override existing styles.